Thermal Comfort in Buildings Explained - HVACR Design

Thermal Comfort in Buildings Explained - HVACR Design

Thermal Comfort in Buildings Explained - HVACR Design
Thermal Comfort in Buildings Explained - HVACR Design

WHAT IS THERMAL COMFORT?

The most commonly used definition for THERMAL COMFORT according to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (Ashrae) is “That condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation”. Although thermal sensitivity varies from one person to another, according to age (the very young and very old being particularly sensitive), gender, dress, activity, cultural habits, etc., the basic principles
behind thermal comfort are largely universal.

The THERMAL COMFORT is experienced via a number of conscious interactions between three personal and environment factors:

  • Physiological : the way our bodies work and interact with our environment;
  • Physical : the main parameters of the environment around us (air temperature, air humidity, air movement, room surface temperature);
  • Socio Psychological: the way we feel as a whole (for example, if we are tired, stressed, happy…) and the kind of social environment we live in.


The physiological aspect
Regulation systems within our bodies continuously strive to balance our heat exchanges with the environment, by speeding up or slowing down our heartbeat to modify our blood flow and regulate heat distribution; by shivering when too cold in order to increase heat production; by sweating more when too hot to reduce skin temperature thanks to evaporation.
A comfortable indoor environment limits the efforts our bodies need to make to regulate body temperature, establishing a good energy balance.

The physical aspect
In the physical environment, thermal energy (heat or cold) is transferred through conduction, radiation and convection.
Conduction is energy transfer via a solid, such as the floor or wall. Convection is energy transfer from a solid to an adjacent gas or fluid (air or water). And radiation is the energy emitted from a surface, such as a radiator.


The socio psychological aspect
An individual’s current emotional state, mood, level of fatigue, etc. will affect their experience of an environment. Expectations play an important role in how an individual experiences the physical world: one would expect a beach to be hot and a mountain lodge to be cool, but more generally, perceptions are likely to based on one’s own
Learn the different factors which affect our thermal comfort in buildings and how we control these conditions using HVACR. We also look at how to optimise the design and efficiency of our built environment using CFD simulations. 
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